1. Field of the Invention
The present invention relates to digital-to-analog and analog-to-digital converter circuits and more particularly to converter circuits employing charge redistribution and transfer techniques and analog-to-digital converter circuits to produce search values for a successive approximation type search used in the conversion technique.
2. Description of the Prior Art
Analog-to-digital and digital-to-analog converter circuits which use combinations of capacitors and switches to produce search voltages and analog signals are known in the art. A circuit of this type is described in the publication "An All-MOS Charge-Redistribution A/D Conversion Technique", R. E. Suarez, P. R. Gray and D. A. Hodges, 1974/SSCC Digest, p. 194, February 1974. In this circuit, at certain places in the approximation it may be impossible to generate the next search value directly and in which case it is necessary to start the entire sequence over. In the present invention, because of the use of charge transfer technology and the unique method of operation, the approximation sequence can always be carried out directly. The present invention also overcomes inherent disadvantages associated with the use of switches and capacitors.